A well or borehole is generally drilled into the ground to recover natural deposits of hydrocarbons and/or other desirable materials trapped in a geological formation in the Earth's crust. A well or borehole is typically drilled using a drill bit attached to a lower end of a drill string. The well or borehole may be drilled to penetrate subsurface geological formation in the Earth's crust which contain the trapped hydrocarbons and/or other materials, As a result, the trapped hydrocarbons and/or materials may be released and/or recovered via the well or borehole.
The BHA is located at the lower end of the drill string and may include the drill bit along with one or more sensors, control mechanisms and/or circuitry. Traditionally, the one or more sensors of the BHA may detect and/or measure one or more downhole measurements associated with one or more properties of the subsurface geological formation and/or fluid or gas which may be contained within the formation. Additionally, the one or more sensors of the BHA may detect and/or measure one or more downhole measurements associated with an orientation and/or a position of the BHA and the drill bit with respect to the subsurface geological formation, the natural deposits of hydrocarbons and/or other materials, and/or the surface of the Earth.
Drilling operations for the drill bit located at the BHA of the drill string may be controlled by one or more operators located at the Earth's surface or at an operations support center located locally or remotely with respect to the well, borehole and/or the drill string. The drill string may be rotated at a rotational rate by a rotary table, or a top drive located at the Earth's surface. The one or more operators may control the rotational rate, an amount of weight-on-bit and/or other operating parameters associated with the drilling process.
It is known that drilling mud may be pumped from the Earth's surface to the drill bit via an interior passage of the drill string. The drilling mud may cool and/or lubricate the drill bit during the drilling process by being pumped downhole via the drill string. Additionally, the drilling mud may transport one or more drill cuttings, which may be cut from the geological formations by the drill bit, uphole back to the Earth's surface. The drilling mud may have a density which may be controlled by the one or more operators to maintain hydrostatic pressure in the borehole at one or more desired levels.
To facilitate successful and desirable drilling operations for the well or borehole, the one or more operators must have access to and/or be aware of the downhole measurements made by the one or more sensors of the BHA. In order for the one or more operators to access the downhole measurements for controlling and/or steering the drill bit and/or a direction of the drill bit, a communication link must be established and/or provided between the one or more operators at the Earth's surface and the BHA of the drill string. A “downlink” is known to be a communication link extending downhole from the Earth's surface to the BHA of the drill string. Based on one or more downhole measurements collected by the one or more sensors located at the BHA of the drill string, the one or more operators may send or transmit one or more commands downhole to the BHA via the downlink. The one or more commands may include one or more instructions for the BHA which may facilitate a change in or a steering of a direction of the drilling by the drill bit.
An “uplink” is known to be a communication link uphole from the BHA of the drill string to the Earth's surface. An uplink is typically a transmission of the data and/or information associated with the one or more downhole measurements which may be detected, measured and/or collected by the one or more sensors located at the BHA. For example, it is often important for an operator to know the orientation of the BHA with respect to the geological formation. Thus, orientation data and/or measurements detected and/or collected by one or more sensors located at the BHA may be transmitted uphole from the BHA to the Earth's surface via the uplink. Additionally, an uplink communication may also be used to confirm that the one or more commands previously transmitted via the downlink were accurately understood b the BHA, the one or more sensors and/or the drill bit of the drill string.
A known method for providing a communication link (i.e., downlink and/or uplink communications) between the Earth's surface and the BHA is mud pulse telemetry. Mud pulse telemetry is a method of sending or transmitting one or more signals, either downlink or uplink communications, by creating one or more pressure and/or flow rate pulses (hereinafter “pressure pulses”) in the drilling mud. The one or more pressure pulses may be detected by one or more sensors at a receiving location which may be located at, near or adjacent to the Earth's surface. For example, in a downlink communication, a change in the pressure or flow rate of drilling mud being pumped down the interior passage of the drill string may be detected by at least one sensors of the BHA. A pattern of the pulses, such as a frequency, a phase, and/or an amplitude, may be representative of the command sent or transmitted by the one or more operators located at Earth's surface. The pattern of the pressure pulses may be detected by at least one sensor of the BHA and may be interpreted such that the command may be understood by the BHA, the one or more sensors and/or the drill bit of the drill string.
Mud pulse telemetry systems are typically classified as one of two types of mud pulse telemetry systems which depend upon the type of pressure pulse generator being used, although “hybrid” mud pulse telemetry systems have also been disclosed. A first type of mud pulse telemetry systems may utilize a valving “poppet” system to generate a series of either positive or negative, and essentially discrete, pressure pulses which are digital representations of transmitted data and/or information. A second type of mud pulse telemetry system, an example of which is disclosed in U.S. Pat. No. 3,309,656, incorporated herein be reference in its entirety, utilizes a rotary valve or a “mud siren” pressure pulse generator which may repeatedly interrupt the downward flow of the drilling mud in the drill string, and thus may cause varying pressure waves or pulses to be generated in the drilling mud at a acoustic carrier frequency that is proportional to a rate of interruption. The data and/or information associated with the one or more downhole measurements which may be detected and/or collected by the one or more sensors of the BHA may be transmitted from the BHA to the Earth's surface by modulating the acoustic carrier frequency. A related design is that of the oscillating valve, as disclosed in U.S. Pat. No. 6,626,253, incorporated herein by reference in its entirety, wherein the rotor oscillates relative to stator, changing directions every 180 degrees, repeatedly interrupting the downward flow of the drilling fluid and causing varying pressure waves or pulses to be generated.
Referring now to the drawings wherein like numerals refer to like parts, FIG. 1 schematically illustrates a known drilling system 100, which may be on-shore or off-shore, in which the present systems and methods for canceling noise and/or echoes in borehole communication may be implemented. The drilling system 100 may be an on-shore drilling system having a drilling rig 10 which includes a drive mechanism 12 to provide a driving torque to a drill string 14. The lower end of the drill string 14 extends into a wellbore 30 and carries a drill bit 16 to drill an underground formation 18. During drilling operations, drilling fluid 20 is drawn from a mud pit 22 on at the Earth's surface 29 via one or more pumps 24, such as, for example, one or more reciprocating pumps. The drilling fluid 20 is circulated through a mud line 26 down through the drill string 14, through the drill bit 16, and back to the surface 29 via an annulus 28 between the drill string 14 and the wall 30 of the wellbore. Upon reaching the surface 29, the drilling fluid 20 is discharged through a line 32 into the mud pit 22 so that drill cuttings, such as, for example, rock and/or other well debris carried uphole in the drilling mud can settle to the bottom of the mud pit 22 before the drilling fluid 20 is recirculated into the drill string 14.
The drill string 14 includes a bottom hole assembly 33 (hereinafter “BHA 33”) which may be located at, near or adjacent to the underground formation 18, the drill bit 16 and/or the wall 30 of the wellbore. The BHA 33 of the drill string 14 may include at least one downhole tool 34. The drilling system 100 may also include a drill collar 110, as shown in FIG. 2, which may be positioned within a portion of the wellbore during or after drilling the wellbore. It should be understood that the BHA 33 of the drill string 14 may include any number of downhole tools and/or other features as known to one of ordinary skill in the art.
The downhole tool 34 may be located and/or positioned within the drill collar 110 as shown in FIG. 2. The downhole tool 34 may contain one or a plurality of known types of telemetry, survey or measurement tools, such as, logging-while-drilling tools (hereinafter “LWD tools”), measuring-while-drilling tools (hereinafter “MWD tools”), near-bit tools, on-bit tools, and/or wireline configurable tools.
The LWD tools may include capabilities for measuring, processing, and storing information, as well as for communicating with surface equipment. Additionally, the LWD tools may include one or more of the following types of logging devices that measure characteristics associated with the formation 18 and/or the wellbore: a resistivity measuring device; a directional resistivity measuring device; a sonic measuring device; a nuclear measuring device; a nuclear magnetic resonance measuring device; a pressure measuring device; a seismic measuring device; an imaging device; a formation sampling device; a natural gamma ray device; a density and photoelectric index device; a neutron porosity device; and a borehole caliper device. It should be understood that the downhole tool 34 may be any LWD tool as known to one or ordinary skill in the skill.
In embodiments, the MWD tools may include one or more devices for measuring characteristics of the drill bit 16 and/or the drill string 14. The MWD tools may include one or more of the following types of measuring devices: a weight-on-bit measuring device; a torque measuring device; a vibration measuring device; a shock measuring device; a stick slip measuring device; a direction measuring device; an inclination measuring device; a natural gamma ray device; a directional survey device; a tool face device; a borehole pressure device; and a temperature device. The MWD tools may detect, collect and/or log data and/or information about the conditions at the drill bit 16, around the underground formation 18, at a front of the drill string 14 and/or at a distance around the drill strings 14. It should be understood that the downhole tool 34 may be any MWD tool as known to one of ordinary skill in the art.
The wireline configurable tool may be a tool commonly conveyed by wireline cable as known to one having ordinary skill in the art. For example, the wireline configurable tool may be a logging tool for sampling or measuring characteristics of the underground formation 18, such as gamma radiation measurements, nuclear measurements, density measurements, and porosity measurements. In embodiments, the downhole tool 34 may be a well completion tool for extracting reservoir fluids after completion of drilling.
The downhole tool 34 may comprise, may include or may incorporate a BHA power source (not shown in the drawings). The BHA power source may be, for example, a downhole motor, a downhole mud motor or any other power generating source as known to one of ordinary skill in the art. The BHA power source may produce and generate electrical power or electrical energy to be distributed throughout the BHA 33 and/or to power the at least one downhole tool 34.
It is known that the downhole tool 34 may be, for example, a MWD tool which may be incorporated into the drill string 14 and/or the near the drill bit 16 for acquisition and/or transmission of downhole measurements, data and/or information. The MWD tool 34 may include an electronic sensor package 36 and a mudflow wellbore telemetry device 38 (hereinafter “telemetry device 38”) for mud pulse telemetry. The telemetry device 38 may selectively block the passage of the drilling fluid 20 through the drill string 14 to cause pressure pulses or changes in the mud line 26 at the Earth's surface. In other words, the telemetry device 38 may be utilized to modulate pressure pulses in the drilling fluid 20 to transmit downhole measurements, data and/or information from the sensor package 36 to the Earth's surface 29. Modulated changes in the pressure of the drilling fluid 20 may be detected by a pressure transducer 40 and a pump piston sensor 42, both of which may be coupled to a surface system processor (not shown in figures). The surface system processor may interpret the modulated changes in the pressure of the drilling fluid 20 to reconstruct the measurements, data and/or information collected and sent by the sensor package 36. The modulation and demodulation of a pressure wave are described in detail in commonly assigned U.S. Pat. No. 5,375,098, which is incorporated by reference herein in its entirety.
The surface system processor may be implemented using any desired combination of hardware and/or software. For example, a personal computer platform, workstation platform, etc. may store on a computer readable medium, for example, a magnetic or optical hard disk and/or random access memory and execute one or more software routines, programs, machine readable code and/or instructions to perform the operations described herein. Additionally or alternatively, the surface system processor may utilize dedicated hardware or logic such as, for example, application specific integrated circuits, configured programmable logic controllers, discrete logic, analog circuitry and/or passive electrical components to perform the functions or operations described herein.
Still further, the surface system processor may be positioned relatively proximate and/or adjacent to the drilling rig 10. In other words, the surface system processor may be substantially co-located with the drilling rig 10. Alternatively, a part of or the entire surface system processor may alternatively be located relatively remote with respect to the drilling rig 10. For example, the surface system processor may be operationally and/or communicatively coupled to the telemetry device 38 via any combination of one or more wireless or hardwired communication links (not shown in the drawings). Such communication links may include communications links via a packet switched network (e.g., the Internet), hardwired telephone lines, cellular communication links and/or other radio frequency based communication links which may utilize any communication protocol as known to one of ordinary skill in the art.
The BHA 33 may include one or more processors or processing units (not shown in the drawings), such as, for example, a microprocessor, and/or an application specific integrated circuit to manipulate and/or analyze downhole measurements, data and/or information collected at a downhole location rather than manipulate and/or analyze the downhole measurements, data and/or information at the surface and/or at the electronic sensor package 36 of the downhole tool 34.
Noise and echo cancellation techniques are traditionally applied at the receiving end of the drilling system 100, such as, for example, at the Earth's surface 29. For example, U.S. Patent Publication No. 2008/0074948, which is incorporated by reference herein in its entirety, describes noise cancellation techniques for detection and downhole compensation for noise that arises as a result of drilling operations. However, known noise cancellation techniques do not adequately cancel noise and/or echoes introduced into drilling fluid 20 which may be moving downhole or uphole within the drill string 14.
Therefore, there is a need for canceling noise and/or echoes within drilling fluid 20 which may be applied at the transmitting end of the system located downhole from the Earth's surface and/or adjacent to the BHA 33. The present invention provides noise and echo cancellation downhole for detection and correction of unwanted signals that may arise as a result of noise and/or echoes, such as, for example, noise and/or echoes of intentional signals that may be reflected off of one or more components of the BHA 33 and/or the underground formation 18.